High-resolution transmission spectroscopy of ultra-hot Jupiter WASP-33b with NEID

TL;DR

This study uses high-resolution spectroscopy with NEID to analyze the atmosphere of ultra-hot Jupiter WASP-33b, confirming some atomic species, detecting a pulsation-induced signal, and highlighting differences between day and terminator atmospheric compositions.

Contribution

First high-resolution transmission spectroscopy of WASP-33b with NEID, confirming atomic detections and revealing atmospheric composition differences between the dayside and terminator.

Findings

Confirmed detection of Hα, Hβ, Hγ, and Ca II triplets.

No significant day-to-night wind detected.

Non-detection of TiO, Ti I, and V I in transmission spectrum.

Abstract

We report an attempt to detect molecular and atomic species in the atmosphere of the ultra-hot Jupiter WASP-33b using the high-resolution echelle spectrograph NEID with a wavelength coverage of 380$-$930 nm. By analyzing the transmission spectrum of WASP-33b using the line-by-line technique and the cross-correlation technique, we confirm previous detection of H$\alpha$, H$\beta$, H$\gamma$, and Ca II infrared triplets. We find no evidence for a significant day-to-night wind in WASP-33b, taking into account the effects of stellar pulsations using a relatively novel GP method and poorly constrained systemic velocity measurements. We also detect the previously reported pre-transit absorption signal, which may be a pulsation mode induced by the planet. Combined with previous CARMENES and HARPS-N observations, we report the non-detection of TiO, Ti I, and V I in the transmission spectrum, while they were already detected in the dayside atmosphere of WASP-33b. This implies a difference in the chemical compositions and abundances between the dayside and terminator atmospheres of WASP-33b, and certainly requires further improvements in the sensitivity of the detection methods.